Genes in Families

Since the first decade of the twentieth century, the patterns of recurrence of specific human phenotypes have been explained in terms of principles first described by Mendel in the garden pea plant. Mendel's second principle—usually referred to as his first1—is called the law of segregation and states that a pair of factors (alleles) that determines some trait separates (segregates) during formation of gametes. In simple terms, a heterozygous (A/a) person will produce two types of gametes with respect to this locus—one containing only A and one containing only a, in equal proportions. Offspring of this person will have a 50–50 chance of inheriting the A allele and a similar chance of inheriting the a allele.

1 Mendel's first law stated that—from the perspective of the phenotype—it mattered not from which parent a particular mutant allele was inherited. For years this principle was thought to be too obvious to be codified as anybody's "law" and was therefore ignored. In fact, however, recent evidence from studies of human disorders suggests that certain genes are "processed" (imprinted) as they move through the gonad and that processing in the testis is different from that in the ovary. Thus, not only is this first mendelian principle important, it was incorrect as originally formulated from observations in peas.more...

Health means fitness well being energy & strength in the broader sense a person in all aspects. It is also a level of functional or metabolic efficiency of an organism often completely human.

When the foundation of the World Health Organization (WHO), in 1948, health was defined as "a state of complete physical, mental, and social well-being and not merely the absence of disease or infirmity.more...